[clang] 340eac0 - [C++20] Implement P2113R0: Changes to the Partial Ordering of Constrained Functions
Yuanfang Chen via cfe-commits
cfe-commits at lists.llvm.org
Tue Oct 18 11:59:22 PDT 2022
Author: Yuanfang Chen
Date: 2022-10-18T11:58:57-07:00
New Revision: 340eac01f7dad6c24cee35dd35f2484098dd6b1a
URL: https://github.com/llvm/llvm-project/commit/340eac01f7dad6c24cee35dd35f2484098dd6b1a
DIFF: https://github.com/llvm/llvm-project/commit/340eac01f7dad6c24cee35dd35f2484098dd6b1a.diff
LOG: [C++20] Implement P2113R0: Changes to the Partial Ordering of Constrained Functions
This implementation matches GCC behavior in that [[ https://eel.is/c++draft/temp.func.order#6.2.1 | temp.func.order p6.2.1 ]] is not implemented [1]. I reached out to the GCC author to confirm that some changes elsewhere to overload resolution are probably needed, but no solution has been developed sufficiently [3].
Most of the wordings are implemented straightforwardly. However,
for [[ https://eel.is/c++draft/temp.func.order#6.2.2 | temp.func.order p6.2.2 ]] "... or if the function parameters that positionally correspond between the two templates are not of the same type", the "same type" is not very clear ([2] is a bug related to this). Here is a quick example
```
template <C T, C U> int f(T, U);
template <typename T, C U> int f(U, T);
int x = f(0, 0);
```
Is the `U` and `T` from different `f`s the "same type"? The answer is NO even though both `U` and `T` are deduced to be `int` in this case. The reason is that `U` and `T` are dependent types, according to [[ https://eel.is/c++draft/temp.over.link#3 | temp.over.link p3 ]], they can not be the "same type".
To check if two function parameters are the "same type":
* For //function template//: compare the function parameter canonical types and return type between two function templates.
* For //class template/partial specialization//: by [[ https://eel.is/c++draft/temp.spec.partial.order#1.2 | temp.spec.partial.order p1.2 ]], compare the injected template arguments between two templates using hashing(TemplateArgument::Profile) is enough.
[1] https://gcc.gnu.org/git/gitweb.cgi?p=gcc.git;h=57b4daf8dc4ed7b669cc70638866ddb00f5b7746
[2] https://github.com/llvm/llvm-project/issues/49308
[3] https://lists.isocpp.org/core/2020/06/index.php#msg9392
Fixes https://github.com/llvm/llvm-project/issues/54039
Fixes https://github.com/llvm/llvm-project/issues/49308 (PR49964)
Reviewed By: royjacobson, #clang-language-wg, mizvekov
Differential Revision: https://reviews.llvm.org/D128750
Added:
Modified:
clang/docs/ReleaseNotes.rst
clang/include/clang/AST/DeclTemplate.h
clang/include/clang/Sema/Sema.h
clang/lib/AST/DeclTemplate.cpp
clang/lib/Sema/SemaConcept.cpp
clang/lib/Sema/SemaOverload.cpp
clang/lib/Sema/SemaTemplate.cpp
clang/lib/Sema/SemaTemplateDeduction.cpp
clang/test/CXX/over/over.match/over.match.best/p1-2a.cpp
clang/test/CXX/temp/temp.decls/temp.fct/temp.func.order/p6.cpp
clang/www/cxx_status.html
Removed:
################################################################################
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 9fe63dd5de840..cb704266df407 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -534,6 +534,9 @@ C++20 Feature Support
which removes the requirement for the ``typename`` keyword in certain contexts.
- Implemented The Equality Operator You Are Looking For (`P2468 <http://wg21.link/p2468r2>`_).
+- Implemented `P2113R0: Proposed resolution for 2019 comment CA 112 <https://wg21.link/P2113R0>`_
+ ([temp.func.order]p6.2.1 is not implemented, matching GCC).
+
C++2b Feature Support
^^^^^^^^^^^^^^^^^^^^^
diff --git a/clang/include/clang/AST/DeclTemplate.h b/clang/include/clang/AST/DeclTemplate.h
index 5cd1de4d24132..ae10744383559 100644
--- a/clang/include/clang/AST/DeclTemplate.h
+++ b/clang/include/clang/AST/DeclTemplate.h
@@ -847,6 +847,15 @@ class RedeclarableTemplateDecl : public TemplateDecl,
/// The first value in the array is the number of specializations/partial
/// specializations that follow.
uint32_t *LazySpecializations = nullptr;
+
+ /// The set of "injected" template arguments used within this
+ /// template.
+ ///
+ /// This pointer refers to the template arguments (there are as
+ /// many template arguments as template parameaters) for the
+ /// template, and is allocated lazily, since most templates do not
+ /// require the use of this information.
+ TemplateArgument *InjectedArgs = nullptr;
};
/// Pointer to the common data shared by all declarations of this
@@ -954,6 +963,14 @@ class RedeclarableTemplateDecl : public TemplateDecl,
getCommonPtr()->InstantiatedFromMember.setPointer(TD);
}
+ /// Retrieve the "injected" template arguments that correspond to the
+ /// template parameters of this template.
+ ///
+ /// Although the C++ standard has no notion of the "injected" template
+ /// arguments for a template, the notion is convenient when
+ /// we need to perform substitutions inside the definition of a template.
+ ArrayRef<TemplateArgument> getInjectedTemplateArgs();
+
using redecl_range = redeclarable_base::redecl_range;
using redecl_iterator = redeclarable_base::redecl_iterator;
@@ -998,15 +1015,6 @@ class FunctionTemplateDecl : public RedeclarableTemplateDecl {
/// template, including explicit specializations and instantiations.
llvm::FoldingSetVector<FunctionTemplateSpecializationInfo> Specializations;
- /// The set of "injected" template arguments used within this
- /// function template.
- ///
- /// This pointer refers to the template arguments (there are as
- /// many template arguments as template parameaters) for the function
- /// template, and is allocated lazily, since most function templates do not
- /// require the use of this information.
- TemplateArgument *InjectedArgs = nullptr;
-
Common() = default;
};
@@ -1106,15 +1114,6 @@ class FunctionTemplateDecl : public RedeclarableTemplateDecl {
return makeSpecIterator(getSpecializations(), true);
}
- /// Retrieve the "injected" template arguments that correspond to the
- /// template parameters of this function template.
- ///
- /// Although the C++ standard has no notion of the "injected" template
- /// arguments for a function template, the notion is convenient when
- /// we need to perform substitutions inside the definition of a function
- /// template.
- ArrayRef<TemplateArgument> getInjectedTemplateArgs();
-
/// Return whether this function template is an abbreviated function template,
/// e.g. `void foo(auto x)` or `template<typename T> void foo(auto x)`
bool isAbbreviated() const {
diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
index 6b422c3897c38..6091a0be01089 100644
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -8329,14 +8329,17 @@ class Sema final {
const NamedDecl *NewInstFrom, TemplateParameterList *New,
const NamedDecl *OldInstFrom, TemplateParameterList *Old, bool Complain,
TemplateParameterListEqualKind Kind,
- SourceLocation TemplateArgLoc = SourceLocation());
+ SourceLocation TemplateArgLoc = SourceLocation(),
+ bool PartialOrdering = false);
bool TemplateParameterListsAreEqual(
TemplateParameterList *New, TemplateParameterList *Old, bool Complain,
TemplateParameterListEqualKind Kind,
- SourceLocation TemplateArgLoc = SourceLocation()) {
+ SourceLocation TemplateArgLoc = SourceLocation(),
+ bool PartialOrdering = false) {
return TemplateParameterListsAreEqual(nullptr, New, nullptr, Old, Complain,
- Kind, TemplateArgLoc);
+ Kind, TemplateArgLoc,
+ PartialOrdering);
}
bool CheckTemplateDeclScope(Scope *S, TemplateParameterList *TemplateParams);
@@ -9021,8 +9024,7 @@ class Sema final {
FunctionTemplateDecl *getMoreSpecializedTemplate(
FunctionTemplateDecl *FT1, FunctionTemplateDecl *FT2, SourceLocation Loc,
TemplatePartialOrderingContext TPOC, unsigned NumCallArguments1,
- unsigned NumCallArguments2, bool Reversed = false,
- bool AllowOrderingByConstraints = true);
+ unsigned NumCallArguments2, bool Reversed = false);
UnresolvedSetIterator
getMostSpecialized(UnresolvedSetIterator SBegin, UnresolvedSetIterator SEnd,
TemplateSpecCandidateSet &FailedCandidates,
diff --git a/clang/lib/AST/DeclTemplate.cpp b/clang/lib/AST/DeclTemplate.cpp
index c419cb7006b5f..9a2932c0bcbd8 100644
--- a/clang/lib/AST/DeclTemplate.cpp
+++ b/clang/lib/AST/DeclTemplate.cpp
@@ -353,6 +353,22 @@ void RedeclarableTemplateDecl::addSpecializationImpl(
SETraits::getDecl(Entry));
}
+ArrayRef<TemplateArgument> RedeclarableTemplateDecl::getInjectedTemplateArgs() {
+ TemplateParameterList *Params = getTemplateParameters();
+ auto *CommonPtr = getCommonPtr();
+ if (!CommonPtr->InjectedArgs) {
+ auto &Context = getASTContext();
+ SmallVector<TemplateArgument, 16> TemplateArgs;
+ Context.getInjectedTemplateArgs(Params, TemplateArgs);
+ CommonPtr->InjectedArgs =
+ new (Context) TemplateArgument[TemplateArgs.size()];
+ std::copy(TemplateArgs.begin(), TemplateArgs.end(),
+ CommonPtr->InjectedArgs);
+ }
+
+ return llvm::makeArrayRef(CommonPtr->InjectedArgs, Params->size());
+}
+
//===----------------------------------------------------------------------===//
// FunctionTemplateDecl Implementation
//===----------------------------------------------------------------------===//
@@ -403,22 +419,6 @@ void FunctionTemplateDecl::addSpecialization(
InsertPos);
}
-ArrayRef<TemplateArgument> FunctionTemplateDecl::getInjectedTemplateArgs() {
- TemplateParameterList *Params = getTemplateParameters();
- Common *CommonPtr = getCommonPtr();
- if (!CommonPtr->InjectedArgs) {
- auto &Context = getASTContext();
- SmallVector<TemplateArgument, 16> TemplateArgs;
- Context.getInjectedTemplateArgs(Params, TemplateArgs);
- CommonPtr->InjectedArgs =
- new (Context) TemplateArgument[TemplateArgs.size()];
- std::copy(TemplateArgs.begin(), TemplateArgs.end(),
- CommonPtr->InjectedArgs);
- }
-
- return llvm::makeArrayRef(CommonPtr->InjectedArgs, Params->size());
-}
-
void FunctionTemplateDecl::mergePrevDecl(FunctionTemplateDecl *Prev) {
using Base = RedeclarableTemplateDecl;
diff --git a/clang/lib/Sema/SemaConcept.cpp b/clang/lib/Sema/SemaConcept.cpp
index e1ebfb1e6f81b..5d8d7a41f821c 100644
--- a/clang/lib/Sema/SemaConcept.cpp
+++ b/clang/lib/Sema/SemaConcept.cpp
@@ -1104,6 +1104,18 @@ NormalizedConstraint::fromConstraintExpr(Sema &S, NamedDecl *D, const Expr *E) {
// - The normal form of an expression (E) is the normal form of E.
// [...]
E = E->IgnoreParenImpCasts();
+
+ // C++2a [temp.param]p4:
+ // [...] If T is not a pack, then E is E', otherwise E is (E' && ...).
+ //
+ // Using the pattern suffices because the partial ordering rules guarantee
+ // the template paramaters are equivalent.
+ if (auto *FoldE = dyn_cast<const CXXFoldExpr>(E)) {
+ assert(FoldE->isRightFold() && FoldE->getOperator() == BO_LAnd);
+ assert(E->IgnoreParenImpCasts() == E);
+ E = FoldE->getPattern();
+ }
+
if (LogicalBinOp BO = E) {
auto LHS = fromConstraintExpr(S, D, BO.getLHS());
if (!LHS)
diff --git a/clang/lib/Sema/SemaOverload.cpp b/clang/lib/Sema/SemaOverload.cpp
index 89df99fb6320f..721056f1f9dab 100644
--- a/clang/lib/Sema/SemaOverload.cpp
+++ b/clang/lib/Sema/SemaOverload.cpp
@@ -9776,19 +9776,13 @@ static bool haveSameParameterTypes(ASTContext &Context, const FunctionDecl *F1,
/// We're allowed to use constraints partial ordering only if the candidates
/// have the same parameter types:
-/// [temp.func.order]p6.2.2 [...] or if the function parameters that
-/// positionally correspond between the two templates are not of the same type,
-/// neither template is more specialized than the other.
/// [over.match.best]p2.6
/// F1 and F2 are non-template functions with the same parameter-type-lists,
/// and F1 is more constrained than F2 [...]
-static bool canCompareFunctionConstraints(Sema &S,
+static bool sameFunctionParameterTypeLists(Sema &S,
const OverloadCandidate &Cand1,
const OverloadCandidate &Cand2) {
- // FIXME: Per P2113R0 we also need to compare the template parameter lists
- // when comparing template functions.
- if (Cand1.Function && Cand2.Function && Cand1.Function->hasPrototype() &&
- Cand2.Function->hasPrototype()) {
+ if (Cand1.Function && Cand2.Function) {
auto *PT1 = cast<FunctionProtoType>(Cand1.Function->getFunctionType());
auto *PT2 = cast<FunctionProtoType>(Cand2.Function->getFunctionType());
if (PT1->getNumParams() == PT2->getNumParams() &&
@@ -10031,15 +10025,14 @@ bool clang::isBetterOverloadCandidate(
isa<CXXConversionDecl>(Cand1.Function) ? TPOC_Conversion
: TPOC_Call,
Cand1.ExplicitCallArguments, Cand2.ExplicitCallArguments,
- Cand1.isReversed() ^ Cand2.isReversed(),
- canCompareFunctionConstraints(S, Cand1, Cand2)))
+ Cand1.isReversed() ^ Cand2.isReversed()))
return BetterTemplate == Cand1.Function->getPrimaryTemplate();
}
// -— F1 and F2 are non-template functions with the same
// parameter-type-lists, and F1 is more constrained than F2 [...],
if (!Cand1IsSpecialization && !Cand2IsSpecialization &&
- canCompareFunctionConstraints(S, Cand1, Cand2)) {
+ sameFunctionParameterTypeLists(S, Cand1, Cand2)) {
Expr *RC1 = Cand1.Function->getTrailingRequiresClause();
Expr *RC2 = Cand2.Function->getTrailingRequiresClause();
if (RC1 && RC2) {
diff --git a/clang/lib/Sema/SemaTemplate.cpp b/clang/lib/Sema/SemaTemplate.cpp
index 44b55427bf132..551e0c3cf3b07 100644
--- a/clang/lib/Sema/SemaTemplate.cpp
+++ b/clang/lib/Sema/SemaTemplate.cpp
@@ -7652,10 +7652,10 @@ bool Sema::CheckTemplateTemplateArgument(TemplateTemplateParmDecl *Param,
if (isTemplateTemplateParameterAtLeastAsSpecializedAs(Params, Template,
Arg.getLocation())) {
- // C++2a[temp.func.order]p2
+ // P2113
+ // C++20[temp.func.order]p2
// [...] If both deductions succeed, the partial ordering selects the
- // more constrained template as described by the rules in
- // [temp.constr.order].
+ // more constrained template (if one exists) as determined below.
SmallVector<const Expr *, 3> ParamsAC, TemplateAC;
Params->getAssociatedConstraints(ParamsAC);
// C++2a[temp.arg.template]p3
@@ -7864,7 +7864,8 @@ Sema::BuildExpressionFromIntegralTemplateArgument(const TemplateArgument &Arg,
static bool MatchTemplateParameterKind(
Sema &S, NamedDecl *New, const NamedDecl *NewInstFrom, NamedDecl *Old,
const NamedDecl *OldInstFrom, bool Complain,
- Sema::TemplateParameterListEqualKind Kind, SourceLocation TemplateArgLoc) {
+ Sema::TemplateParameterListEqualKind Kind, SourceLocation TemplateArgLoc,
+ bool PartialOrdering) {
// Check the actual kind (type, non-type, template).
if (Old->getKind() != New->getKind()) {
if (Complain) {
@@ -7952,11 +7953,11 @@ static bool MatchTemplateParameterKind(
(Kind == Sema::TPL_TemplateMatch
? Sema::TPL_TemplateTemplateParmMatch
: Kind),
- TemplateArgLoc))
+ TemplateArgLoc, PartialOrdering))
return false;
}
- if (Kind != Sema::TPL_TemplateTemplateArgumentMatch &&
+ if (!PartialOrdering && Kind != Sema::TPL_TemplateTemplateArgumentMatch &&
!isa<TemplateTemplateParmDecl>(Old)) {
const Expr *NewC = nullptr, *OldC = nullptr;
@@ -8049,7 +8050,8 @@ void DiagnoseTemplateParameterListArityMismatch(Sema &S,
bool Sema::TemplateParameterListsAreEqual(
const NamedDecl *NewInstFrom, TemplateParameterList *New,
const NamedDecl *OldInstFrom, TemplateParameterList *Old, bool Complain,
- TemplateParameterListEqualKind Kind, SourceLocation TemplateArgLoc) {
+ TemplateParameterListEqualKind Kind, SourceLocation TemplateArgLoc,
+ bool PartialOrdering) {
if (Old->size() != New->size() && Kind != TPL_TemplateTemplateArgumentMatch) {
if (Complain)
DiagnoseTemplateParameterListArityMismatch(*this, New, Old, Kind,
@@ -8081,7 +8083,7 @@ bool Sema::TemplateParameterListsAreEqual(
if (!MatchTemplateParameterKind(*this, *NewParm, NewInstFrom, *OldParm,
OldInstFrom, Complain, Kind,
- TemplateArgLoc))
+ TemplateArgLoc, PartialOrdering))
return false;
++NewParm;
@@ -8098,7 +8100,7 @@ bool Sema::TemplateParameterListsAreEqual(
for (; NewParm != NewParmEnd; ++NewParm) {
if (!MatchTemplateParameterKind(*this, *NewParm, NewInstFrom, *OldParm,
OldInstFrom, Complain, Kind,
- TemplateArgLoc))
+ TemplateArgLoc, PartialOrdering))
return false;
}
}
@@ -8112,7 +8114,7 @@ bool Sema::TemplateParameterListsAreEqual(
return false;
}
- if (Kind != TPL_TemplateTemplateArgumentMatch) {
+ if (!PartialOrdering && Kind != TPL_TemplateTemplateArgumentMatch) {
const Expr *NewRC = New->getRequiresClause();
const Expr *OldRC = Old->getRequiresClause();
diff --git a/clang/lib/Sema/SemaTemplateDeduction.cpp b/clang/lib/Sema/SemaTemplateDeduction.cpp
index 822ec1828dce4..00b1cf1224e2b 100644
--- a/clang/lib/Sema/SemaTemplateDeduction.cpp
+++ b/clang/lib/Sema/SemaTemplateDeduction.cpp
@@ -5172,43 +5172,26 @@ static bool isAtLeastAsSpecializedAs(Sema &S,
/// candidate with a reversed parameter order. In this case, the corresponding
/// P/A pairs between FT1 and FT2 are reversed.
///
-/// \param AllowOrderingByConstraints If \c is false, don't check whether one
-/// of the templates is more constrained than the other. Default is true.
-///
/// \returns the more specialized function template. If neither
/// template is more specialized, returns NULL.
FunctionTemplateDecl *Sema::getMoreSpecializedTemplate(
FunctionTemplateDecl *FT1, FunctionTemplateDecl *FT2, SourceLocation Loc,
TemplatePartialOrderingContext TPOC, unsigned NumCallArguments1,
- unsigned NumCallArguments2, bool Reversed,
- bool AllowOrderingByConstraints) {
-
- auto JudgeByConstraints = [&]() -> FunctionTemplateDecl * {
- if (!AllowOrderingByConstraints)
- return nullptr;
- llvm::SmallVector<const Expr *, 3> AC1, AC2;
- FT1->getAssociatedConstraints(AC1);
- FT2->getAssociatedConstraints(AC2);
- bool AtLeastAsConstrained1, AtLeastAsConstrained2;
- if (IsAtLeastAsConstrained(FT1, AC1, FT2, AC2, AtLeastAsConstrained1))
- return nullptr;
- if (IsAtLeastAsConstrained(FT2, AC2, FT1, AC1, AtLeastAsConstrained2))
- return nullptr;
- if (AtLeastAsConstrained1 == AtLeastAsConstrained2)
- return nullptr;
- return AtLeastAsConstrained1 ? FT1 : FT2;
- };
+ unsigned NumCallArguments2, bool Reversed) {
bool Better1 = isAtLeastAsSpecializedAs(*this, Loc, FT1, FT2, TPOC,
NumCallArguments1, Reversed);
bool Better2 = isAtLeastAsSpecializedAs(*this, Loc, FT2, FT1, TPOC,
NumCallArguments2, Reversed);
+ // C++ [temp.deduct.partial]p10:
+ // F is more specialized than G if F is at least as specialized as G and G
+ // is not at least as specialized as F.
if (Better1 != Better2) // We have a clear winner
return Better1 ? FT1 : FT2;
if (!Better1 && !Better2) // Neither is better than the other
- return JudgeByConstraints();
+ return nullptr;
// C++ [temp.deduct.partial]p11:
// ... and if G has a trailing function parameter pack for which F does not
@@ -5260,7 +5243,61 @@ FunctionTemplateDecl *Sema::getMoreSpecializedTemplate(
}
}
- return JudgeByConstraints();
+ if (!Context.getLangOpts().CPlusPlus20 || isa<CXXDeductionGuideDecl>(FD1) ||
+ isa<CXXDeductionGuideDecl>(FD2))
+ return nullptr;
+
+ // Match GCC on not implementing [temp.func.order]p6.2.1.
+
+ // C++20 [temp.func.order]p6:
+ // If deduction against the other template succeeds for both transformed
+ // templates, constraints can be considered as follows:
+
+ // C++20 [temp.func.order]p6.1:
+ // If their template-parameter-lists (possibly including template-parameters
+ // invented for an abbreviated function template ([dcl.fct])) or function
+ // parameter lists
diff er in length, neither template is more specialized
+ // than the other.
+ TemplateParameterList *TPL1 = FT1->getTemplateParameters();
+ TemplateParameterList *TPL2 = FT2->getTemplateParameters();
+ if (TPL1->size() != TPL2->size() || NumParams1 != NumParams2)
+ return nullptr;
+
+ // C++20 [temp.func.order]p6.2.2:
+ // Otherwise, if the corresponding template-parameters of the
+ // template-parameter-lists are not equivalent ([temp.over.link]) or if the
+ // function parameters that positionally correspond between the two
+ // templates are not of the same type, neither template is more specialized
+ // than the other.
+ if (!TemplateParameterListsAreEqual(
+ TPL1, TPL2, false, Sema::TPL_TemplateMatch, SourceLocation(), true))
+ return nullptr;
+
+ for (unsigned i = 0; i < NumParams1; ++i)
+ if (!Context.hasSameType(FD1->getParamDecl(i)->getType(),
+ FD2->getParamDecl(i)->getType()))
+ return nullptr;
+
+ // C++20 [temp.func.order]p6.3:
+ // Otherwise, if the context in which the partial ordering is done is
+ // that of a call to a conversion function and the return types of the
+ // templates are not the same, then neither template is more specialized
+ // than the other.
+ if (TPOC == TPOC_Conversion &&
+ !Context.hasSameType(FD1->getReturnType(), FD2->getReturnType()))
+ return nullptr;
+
+ llvm::SmallVector<const Expr *, 3> AC1, AC2;
+ FT1->getAssociatedConstraints(AC1);
+ FT2->getAssociatedConstraints(AC2);
+ bool AtLeastAsConstrained1, AtLeastAsConstrained2;
+ if (IsAtLeastAsConstrained(FT1, AC1, FT2, AC2, AtLeastAsConstrained1))
+ return nullptr;
+ if (IsAtLeastAsConstrained(FT2, AC2, FT1, AC1, AtLeastAsConstrained2))
+ return nullptr;
+ if (AtLeastAsConstrained1 == AtLeastAsConstrained2)
+ return nullptr;
+ return AtLeastAsConstrained1 ? FT1 : FT2;
}
/// Determine if the two templates are equivalent.
@@ -5438,7 +5475,7 @@ static bool isAtLeastAsSpecializedAs(Sema &S, QualType T1, QualType T2,
}
namespace {
-// A dummy pass to return nullptr instead of P2 when performing "more
+// A dummy class to return nullptr instead of P2 when performing "more
// specialized than primary" check.
struct GetP2 {
template <typename T1, typename T2,
@@ -5452,6 +5489,52 @@ struct GetP2 {
return nullptr;
}
};
+
+// The assumption is that two template argument lists have the same size.
+struct TemplateArgumentListAreEqual {
+ ASTContext &Ctx;
+ TemplateArgumentListAreEqual(ASTContext &Ctx) : Ctx(Ctx) {}
+
+ template <typename T1, typename T2,
+ std::enable_if_t<std::is_same<T1, T2>::value, bool> = true>
+ bool operator()(T1 *PS1, T2 *PS2) {
+ ArrayRef<TemplateArgument> Args1 = PS1->getTemplateArgs().asArray(),
+ Args2 = PS2->getTemplateArgs().asArray();
+
+ for (unsigned I = 0, E = Args1.size(); I < E; ++I) {
+ // We use profile, instead of structural comparison of the arguments,
+ // because canonicalization can't do the right thing for dependent
+ // expressions.
+ llvm::FoldingSetNodeID IDA, IDB;
+ Args1[I].Profile(IDA, Ctx);
+ Args2[I].Profile(IDB, Ctx);
+ if (IDA != IDB)
+ return false;
+ }
+ return true;
+ }
+
+ template <typename T1, typename T2,
+ std::enable_if_t<!std::is_same<T1, T2>::value, bool> = true>
+ bool operator()(T1 *Spec, T2 *Primary) {
+ ArrayRef<TemplateArgument> Args1 = Spec->getTemplateArgs().asArray(),
+ Args2 = Primary->getInjectedTemplateArgs();
+
+ for (unsigned I = 0, E = Args1.size(); I < E; ++I) {
+ // We use profile, instead of structural comparison of the arguments,
+ // because canonicalization can't do the right thing for dependent
+ // expressions.
+ llvm::FoldingSetNodeID IDA, IDB;
+ Args1[I].Profile(IDA, Ctx);
+ // Unlike the specialization arguments, the injected arguments are not
+ // always canonical.
+ Ctx.getCanonicalTemplateArgument(Args2[I]).Profile(IDB, Ctx);
+ if (IDA != IDB)
+ return false;
+ }
+ return true;
+ }
+};
} // namespace
/// Returns the more specialized template specialization between T1/P1 and
@@ -5491,52 +5574,81 @@ getMoreSpecialized(Sema &S, QualType T1, QualType T2, TemplateLikeDecl *P1,
if (IsMoreSpecialThanPrimaryCheck && !Better2)
return P1;
+ // C++ [temp.deduct.partial]p10:
+ // F is more specialized than G if F is at least as specialized as G and G
+ // is not at least as specialized as F.
+ if (Better1 != Better2) // We have a clear winner
+ return Better1 ? P1 : GetP2()(P1, P2);
+
if (!Better1 && !Better2)
return nullptr;
- if (Better1 && Better2) {
- // This a speculative fix for CWG1432 (Similar to the fix for CWG1395) that
- // there is no wording or even resolution for this issue.
- bool ClangABICompat15 = S.Context.getLangOpts().getClangABICompat() <=
- LangOptions::ClangABI::Ver15;
- if (!ClangABICompat15) {
- auto *TST1 = cast<TemplateSpecializationType>(T1);
- auto *TST2 = cast<TemplateSpecializationType>(T2);
- const TemplateArgument &TA1 = TST1->template_arguments().back();
- if (TA1.getKind() == TemplateArgument::Pack) {
- assert(TST1->getNumArgs() == TST2->getNumArgs());
- const TemplateArgument &TA2 = TST2->template_arguments().back();
- assert(TA2.getKind() == TemplateArgument::Pack);
- unsigned PackSize1 = TA1.pack_size();
- unsigned PackSize2 = TA2.pack_size();
- bool IsPackExpansion1 =
- PackSize1 && TA1.pack_elements().back().isPackExpansion();
- bool IsPackExpansion2 =
- PackSize2 && TA2.pack_elements().back().isPackExpansion();
- if (PackSize1 != PackSize2 && IsPackExpansion1 != IsPackExpansion2) {
- if (PackSize1 > PackSize2 && IsPackExpansion1)
- return GetP2()(P1, P2);
- if (PackSize1 < PackSize2 && IsPackExpansion2)
- return P1;
- }
+ // This a speculative fix for CWG1432 (Similar to the fix for CWG1395) that
+ // there is no wording or even resolution for this issue.
+ bool ClangABICompat15 = S.Context.getLangOpts().getClangABICompat() <=
+ LangOptions::ClangABI::Ver15;
+ if (!ClangABICompat15) {
+ auto *TST1 = cast<TemplateSpecializationType>(T1);
+ auto *TST2 = cast<TemplateSpecializationType>(T2);
+ const TemplateArgument &TA1 = TST1->template_arguments().back();
+ if (TA1.getKind() == TemplateArgument::Pack) {
+ assert(TST1->getNumArgs() == TST2->getNumArgs());
+ const TemplateArgument &TA2 = TST2->template_arguments().back();
+ assert(TA2.getKind() == TemplateArgument::Pack);
+ unsigned PackSize1 = TA1.pack_size();
+ unsigned PackSize2 = TA2.pack_size();
+ bool IsPackExpansion1 =
+ PackSize1 && TA1.pack_elements().back().isPackExpansion();
+ bool IsPackExpansion2 =
+ PackSize2 && TA2.pack_elements().back().isPackExpansion();
+ if (PackSize1 != PackSize2 && IsPackExpansion1 != IsPackExpansion2) {
+ if (PackSize1 > PackSize2 && IsPackExpansion1)
+ return GetP2()(P1, P2);
+ if (PackSize1 < PackSize2 && IsPackExpansion2)
+ return P1;
}
}
-
- llvm::SmallVector<const Expr *, 3> AC1, AC2;
- P1->getAssociatedConstraints(AC1);
- P2->getAssociatedConstraints(AC2);
- bool AtLeastAsConstrained1, AtLeastAsConstrained2;
- if (S.IsAtLeastAsConstrained(P1, AC1, P2, AC2, AtLeastAsConstrained1) ||
- (IsMoreSpecialThanPrimaryCheck && !AtLeastAsConstrained1))
- return nullptr;
- if (S.IsAtLeastAsConstrained(P2, AC2, P1, AC1, AtLeastAsConstrained2))
- return nullptr;
- if (AtLeastAsConstrained1 == AtLeastAsConstrained2)
- return nullptr;
- return AtLeastAsConstrained1 ? P1 : GetP2()(P1, P2);
}
- return Better1 ? P1 : GetP2()(P1, P2);
+ if (!S.Context.getLangOpts().CPlusPlus20)
+ return nullptr;
+
+ // Match GCC on not implementing [temp.func.order]p6.2.1.
+
+ // C++20 [temp.func.order]p6:
+ // If deduction against the other template succeeds for both transformed
+ // templates, constraints can be considered as follows:
+
+ TemplateParameterList *TPL1 = P1->getTemplateParameters();
+ TemplateParameterList *TPL2 = P2->getTemplateParameters();
+ if (TPL1->size() != TPL2->size())
+ return nullptr;
+
+ // C++20 [temp.func.order]p6.2.2:
+ // Otherwise, if the corresponding template-parameters of the
+ // template-parameter-lists are not equivalent ([temp.over.link]) or if the
+ // function parameters that positionally correspond between the two
+ // templates are not of the same type, neither template is more specialized
+ // than the other.
+ if (!S.TemplateParameterListsAreEqual(
+ TPL1, TPL2, false, Sema::TPL_TemplateMatch, SourceLocation(), true))
+ return nullptr;
+
+ if (!TemplateArgumentListAreEqual(S.getASTContext())(P1, P2))
+ return nullptr;
+
+ llvm::SmallVector<const Expr *, 3> AC1, AC2;
+ P1->getAssociatedConstraints(AC1);
+ P2->getAssociatedConstraints(AC2);
+ bool AtLeastAsConstrained1, AtLeastAsConstrained2;
+ if (S.IsAtLeastAsConstrained(P1, AC1, P2, AC2, AtLeastAsConstrained1) ||
+ (IsMoreSpecialThanPrimaryCheck && !AtLeastAsConstrained1))
+ return nullptr;
+ if (S.IsAtLeastAsConstrained(P2, AC2, P1, AC1, AtLeastAsConstrained2))
+ return nullptr;
+ if (AtLeastAsConstrained1 == AtLeastAsConstrained2)
+ return nullptr;
+ return AtLeastAsConstrained1 ? P1 : GetP2()(P1, P2);
}
/// Returns the more specialized class template partial specialization
@@ -5596,17 +5708,11 @@ Sema::getMoreSpecializedPartialSpecialization(
bool Sema::isMoreSpecializedThanPrimary(
VarTemplatePartialSpecializationDecl *Spec, TemplateDeductionInfo &Info) {
- TemplateDecl *Primary = Spec->getSpecializedTemplate();
- // FIXME: Cache the injected template arguments rather than recomputing
- // them for each partial specialization.
- SmallVector<TemplateArgument, 8> PrimaryArgs;
- Context.getInjectedTemplateArgs(Primary->getTemplateParameters(),
- PrimaryArgs);
-
+ VarTemplateDecl *Primary = Spec->getSpecializedTemplate();
TemplateName CanonTemplate =
Context.getCanonicalTemplateName(TemplateName(Primary));
QualType PrimaryT = Context.getTemplateSpecializationType(
- CanonTemplate, PrimaryArgs);
+ CanonTemplate, Primary->getInjectedTemplateArgs());
QualType PartialT = Context.getTemplateSpecializationType(
CanonTemplate, Spec->getTemplateArgs().asArray());
diff --git a/clang/test/CXX/over/over.match/over.match.best/p1-2a.cpp b/clang/test/CXX/over/over.match/over.match.best/p1-2a.cpp
index 047d3dc13cc31..dae1ba760cc20 100644
--- a/clang/test/CXX/over/over.match/over.match.best/p1-2a.cpp
+++ b/clang/test/CXX/over/over.match/over.match.best/p1-2a.cpp
@@ -98,26 +98,31 @@ namespace non_template
static_assert(is_same_v<decltype(bar<int>()), void>); // expected-error {{call to 'bar' is ambiguous}}
template<typename T>
- constexpr int goo(int a) requires AtLeast2<int> && true {
+ constexpr int goo(int a) requires AtLeast2<int> && true { // expected-note {{candidate function}}
return 1;
}
template<typename T>
- constexpr int goo(const int b) requires AtLeast2<int> {
+ constexpr int goo(const int b) requires AtLeast2<int> { // expected-note {{candidate function}}
return 2;
}
- // Only trailing requires clauses of redeclarations are compared for overload resolution.
+ // [temp.func.order] p5
+ // Since, in a call context, such type deduction considers only parameters
+ // for which there are explicit call arguments, some parameters are ignored
+ // (namely, function parameter packs, parameters with default arguments, and
+ // ellipsis parameters).
template<typename T>
- constexpr int doo(int a, ...) requires AtLeast2<int> && true { // expected-note {{candidate function}}
+ constexpr int doo(int a, ...) requires AtLeast2<int> && true {
return 1;
}
template<typename T>
- constexpr int doo(int b) requires AtLeast2<int> { // expected-note {{candidate function}}
+ constexpr int doo(int b) requires AtLeast2<int> {
return 2;
}
- static_assert(goo<int>(1) == 1);
- static_assert(doo<int>(2) == 1); // expected-error {{call to 'doo' is ambiguous}}
+ // By temp.func.order-6.2.2, this is ambiguous because parameter a and b have
diff erent types.
+ static_assert(goo<int>(1) == 1); // expected-error {{call to 'goo' is ambiguous}}
+ static_assert(doo<int>(2) == 1);
}
diff --git a/clang/test/CXX/temp/temp.decls/temp.fct/temp.func.order/p6.cpp b/clang/test/CXX/temp/temp.decls/temp.fct/temp.func.order/p6.cpp
index d2c7ec91c3fc8..bdd1c376243bb 100644
--- a/clang/test/CXX/temp/temp.decls/temp.fct/temp.func.order/p6.cpp
+++ b/clang/test/CXX/temp/temp.decls/temp.fct/temp.func.order/p6.cpp
@@ -1,10 +1,18 @@
// RUN: %clang_cc1 -fsyntax-only -verify -std=c++20 %s
-struct A;
-struct B;
-
template <typename> constexpr bool True = true;
template <typename T> concept C = True<T>;
+template <typename T> concept D = C<T> && sizeof(T) > 2;
+template <typename T> concept E = D<T> && alignof(T) > 1;
+
+struct A {};
+template <typename, auto, int, A, typename...> struct S {};
+template <typename, auto, int, A, auto...> struct S2 {};
+template <typename T, typename U> struct X {};
+
+namespace p6 {
+
+struct B;
void f(C auto &, auto &) = delete;
template <C Q> void f(Q &, C auto &);
@@ -13,14 +21,125 @@ void g(struct A *ap, struct B *bp) {
f(*ap, *bp);
}
-template <typename T, typename U> struct X {};
-
+#if 0
+// FIXME: [temp.func.order]p6.2.1 is not implemented, matching GCC.
template <typename T, C U, typename V> bool operator==(X<T, U>, V) = delete;
template <C T, C U, C V> bool operator==(T, X<U, V>);
bool h() {
return X<void *, int>{} == 0;
}
+#endif
+
+template<C T, C auto M, int W, A S,
+ template<typename, auto, int, A, typename...> class U,
+ typename... Z>
+void foo(T, U<T, M, W, S, Z...>) = delete;
+template<C T, D auto M, int W, A S,
+ template<typename, auto, int, A, typename...> class U,
+ typename... Z>
+void foo(T, U<T, M, W, S, Z...>) = delete;
+template<C T, E auto M, int W, A S,
+ template<typename, auto, int, A, typename...> class U,
+ typename... Z>
+void foo(T, U<T, M, W, S, Z...>);
+
+// check auto template parameter pack.
+template<C T, auto M, int W, A S,
+ template<typename, auto, int, A, auto...> class U,
+ C auto... Z>
+void foo2(T, U<T, M, W, S, Z...>) = delete;
+template<C T, auto M, int W, A S,
+ template<typename, auto, int, A, auto...> class U,
+ D auto... Z>
+void foo2(T, U<T, M, W, S, Z...>) = delete;
+template<C T, auto M, int W, A S,
+ template<typename, auto, int, A, auto...> class U,
+ E auto... Z>
+void foo2(T, U<T, M, W, S, Z...>);
+
+void bar(S<int, 1, 1, A{}, int> s, S2<int, 1, 1, A{}, 0, 0u> s2) {
+ foo(0, s);
+ foo2(0, s2);
+}
+
+template<C auto... T> void bar2();
+template<D auto... T> void bar2() = delete;
+
+} // namespace p6
+
+namespace TestConversionFunction {
+struct Y {
+ template<C T, typename U> operator X<T, U>(); // expected-note {{candidate function [with T = int, U = int]}}
+ template<typename T, typename U> operator X<U, T>(); // expected-note {{candidate function [with T = int, U = int]}}
+};
+
+X<int,int> f() {
+ return Y{}; // expected-error {{conversion from 'Y' to 'X<int, int>' is ambiguous}}
+}
+}
+
+namespace ClassPartialSpecPartialOrdering {
+template<D T> struct Y { Y()=delete; }; // expected-note {{template is declared here}}
+template<C T> struct Y<T> {}; // expected-error {{class template partial specialization is not more specialized than the primary template}}
+
+template<C T, int I> struct Y1 { Y1()=delete; };
+template<D T> struct Y1<T, 2> { Y1()=delete; };
+template<E T> struct Y1<T, 1+1> {};
+
+template<class T, int I, int U> struct Y2 {};
+template<class T, int I> struct Y2<T*, I, I+2> {}; // expected-note {{partial specialization matches}}
+template<C T, int I> struct Y2<T*, I, I+1+1> {}; // expected-note {{partial specialization matches}}
+
+template<C T, C auto I, int W, A S, template<typename, auto, int, A, typename...> class U, typename... Z>
+struct Y3 { Y3()=delete; };
+template<C T, D auto I, int W, A S, template<typename, auto, int, A, typename...> class U, typename... Z>
+struct Y3<T, I, W, S, U, Z...> { Y3()=delete; };
+template<C T, E auto I, int W, A S, template<typename, auto, int, A, typename...> class U, typename... Z>
+struct Y3<T, I, W, S, U, Z...> {};
+
+void f() {
+ Y1<int, 2> a;
+ Y2<char*, 1, 3> b; // expected-error {{ambiguous partial specializations}}
+ Y3<int, 1, 1, A{}, S, int> c;
+}
+
+template<C T, C V> struct Y4; // expected-note {{template is declared here}}
+template<D T, C V> struct Y4<V, T>; // expected-error {{class template partial specialization is not more specialized than the primary template}}
+
+template<C auto T> struct W1;
+template<D auto T> struct W1<T> {};
+
+template<C auto... T> struct W2;
+template<D auto... T> struct W2<T...> {};
+
+template<class T, class U>
+concept C1 = C<T> && C<U>;
+template<class T, class U>
+concept D1 = D<T> && C<U>;
+
+template<C1<A> auto T> struct W3;
+template<D1<A> auto T> struct W3<T> {};
+
+template<C1<A> auto... T> struct W4;
+template<D1<A> auto... T> struct W4<T...> {};
+
+// FIXME: enable once Clang support non-trivial auto on NTTP.
+// template<C auto* T> struct W5;
+// template<D auto* T> struct W5<T> {};
+
+// FIXME: enable once Clang support non-trivial auto on NTTP.
+// template<C auto& T> struct W6;
+// template<D auto& T> struct W6<T> {};
+
+struct W1<0> w1;
+struct W2<0> w2;
+struct W3<0> w3;
+struct W4<0> w4;
+// FIXME: enable once Clang support non-trivial auto on NTTP.
+// struct W5<(int*)nullptr> w5;
+// struct W6<w5> w6;
+}
namespace PR53640 {
diff --git a/clang/www/cxx_status.html b/clang/www/cxx_status.html
index 632590a131a8b..cbea6bb5e1e26 100755
--- a/clang/www/cxx_status.html
+++ b/clang/www/cxx_status.html
@@ -963,7 +963,7 @@ <h2 id="cxx20">C++20 implementation status</h2>
</tr>
<tr>
<td><a href="https://wg21.link/p2113r0">P2113R0</a></td>
- <td rowspan="1" class="none" align="center">No</td>
+ <td rowspan="1" class="unreleased" align="center">Clang 16</td>
</tr>
<!-- Albuquerque papers -->
<tr>
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